As part of the effort to map and sequence the human genome, we have been involved in an ongoing effort to develop a multilocus genetic map of the mouse as the model mammalian system. Most of this work has been accomplished by the genetic analysis of the progeny of two genetic crosses, an interspecies and an intersubspecies backcross. DNAs from the progeny of these crosses have been typed for a variety of polymorphic reference loci to permit mapping of unknown markers to specific positions on the linkage map. These studies have resulted in the chromosomal mapping of a large number of genes including various genes expressed in nervous tissue, cyclin genes, heat shock proteins, transcriptional regulators, microtubule associated protein genes and homeobox genes. Several of these genes map at or near known mouse mutations and therefore are potential candidates for these mutations. Thus, one gene specifically expressed in brain was mapped near the coloboma neurological mutation and shown to be deleted in mutant coloboma mice. Another gene encoding a major stuctural component of cartilage was mapped near the cmd (cartilage matrix deficiency) mutation, and cmd mice were shown to have a 7 b deletion of this gene.